1. Field of the Invention
The present invention relates to a projection type display device which utilizes one optical unit including an optical system for illumination, image displaying elements, and an optical system for projecting thereby to project a plurality of images, which are displayed on a plurality of image areas established in one image displaying element, to a plurality of screens. The present invention further relates to an image displaying method of displaying the above images on the screens.
2. Description of the Related Art
Projection type display devices (i.e. projectors) are adapted to project an image on a screen such that the image is displayed in a liquid crystal panel as being a type of image displaying element (light modulation element) and enlarged by an optical system for projecting. Such projectors conventionally have a variety of structures. These projectors are in heavy usage for families and business scenes. The projection type display devices are roughly classified to front projection type display devices for each projecting an image on a screen from before and rear projection type display devices for each projecting an image on a screen from behind. In these projection type display devices, there is normally adopted a structural form for projecting an image displayed in one image displaying element on a screen in enlargement. In some applications, there also exists a structural form for displaying an image on first and second screens in enlargement with the use of a projector. Such a structural form is disclosed in Japanese Patent Publication Laid-open No. 2006-11237.
FIG. 1 is a structural view showing a display system as an example of the conventional projection type display device. FIG. 2 is a view showing an image displayed in a liquid crystal panel in a projector of FIG. 1. In addition, FIGS. 3A and 3B are views each showing a video split device of FIG. 1.
In FIG. 1, the shown display system 100 is disclosed in Japanese Patent Publication Laid-open No. 2006-11237. The display system 100 will be described with reference to this publication in brief.
The display system 100 as one example of the conventional projection type display device of FIG. 1 is arranged in a vehicle such as automobile. The display system 100 includes a projector 110, a video split device 120, a first screen 131, and a second screen 132, all arranged in the vehicle.
The projector 110 is attached to a ceiling inside a vehicle cabin, while the first and second screens 131, 132 are installed in an instrument panel near a driver's seat. The video split device 120 is arranged between the projector 110 and the first and second screens 131, 132 to optically divide projection light flux emitted from the projector 110 into multiple image lights.
In addition, there are arranged various in-car instruments, for example, a navigation system 142, an audio instrument 143, and an air-conditioning apparatus 144, all connected to the projector 110 through a control circuit 141. While, the control circuit 141 outputs video signals to be projected on the projector 110 on receipt of the state information about the in-car instruments.
As shown in FIG. 2, the projector 110 employs a liquid crystal panel 112 as the image displaying element. The liquid crystal panel 112 comprises one image area 112a displaying map information and another image area 112b displaying audio information.
As shown in FIG. 3A, for example, the video split device 120 utilizes a single prism 121 having two reflecting surfaces in order to optically divide projection light flux emitted from the projector 110 into respective directions of the first and second screens 131, 132. Alternatively, as shown in FIG. 3B, the single prism 121 of FIG. 3A may be replaced by two prisms 122, 123 each having a plurality of reflecting surfaces for the same purpose as above.
Then, the video split device 120 divides an image emitted from the projector 110 so that resulting split images are respectively projected on the first screen 131 and the second screen 132. In this way, the disclosed display system 100 is adapted to use the liquid crystal panel (image displaying element) 112 in the projector 110 effectively.